Watertight flywheel housing for boats using a stern drive system

ABSTRACT

The present invention provides a stern drive propulsion system that includes an internal combustion engine having a flywheel and a watertight housing that sealingly encloses the flywheel relative to the surrounding environment. The housing may support a starter coupled to the flywheel and extending toward the transom of a boat. A starter seal is provided to seal corresponding interface surfaces of the starter and the flywheel housing.

BACKGROUND OF INVENTION

[0001] The present invention generally relates to a structural arrangement for preventing water entry in a boat propulsion system and, more particularly, to an improved arrangement for preventing the entry of water into the flywheel housing of a stern drive.

[0002]FIG. 1 shows one example of a commonly used marine propulsion system having a stern drive 2, in which an internal combustion engine 4 is mounted within the hull 6 of a boat 8 and to a propulsion unit 10 that is mounted outside of hull 6. The engine 4 drives the stern drive 2 by an output shaft (not shown) that extends through transom 14 of boat 8. One common practice is to provide some form of elastic coupling between the output shaft of engine 4 and an input shaft of propulsion unit 10 so as to accommodate angular misalignments. The elastic coupling permits movement of engine 4 so as to absorb vibrations by its resilient support. These flexible couplings are normally positioned in proximity to a flywheel 16 of engine 4 to provide damping at the desired location.

[0003] Although this type of arrangement is generally satisfactory, it has been a common practice to provide a flywheel housing 18 or cover that encircles the flywheel 16 but which, as shown in FIG. 2, has a relatively large opening 32 that is positioned in proximity to the flexible coupling 1 3 and normally encircles it. Unfortunately, because. of the presence of such an opening in the flywheel housing 18, there is a high probability that water may enter into the interior of the flywheel housing 18. The large diameter of opening 32 places the lower peripheral edge quite low in the watercraft and hence it is prone to the likelihood of bilge water entering therethrough. When water enters flywheel housing 18, rotation of flywheel 16 throws the water in contact with starter 35 of engine 4. The water can readily cause corrosion of the starter and/or electrical shorts which can render its operation either difficult or, in some instances, inoperative.

[0004] Known systems purport to alleviate and/or prevent the entry of water. These systems implement a “water slinger” to discharge water entering the interior of the flywheel housing, best shown FIG. 2. That is, flywheel housing 18 is formed with a water discharge opening 37 that is disposed slightly above the lower end of flywheel housing 18 and in the direction of rotation of flywheel 16. The water discharge opening 37 is also located below, or before, the location of starter 35. A protruding lip 38 overlies the discharge opening 37 so that any water which may enter flywheel housing 18 should, in theory, be thrown upwardly due to deflection caused by lip 38 and enter the discharge opening 37. A conduit 39 extends from the discharge opening 37 to a discharge point 41 above the highest level of anticipated water in the hull to discharge water from the flywheel housing.

[0005] Unfortunately, in practice, although lip 38 may deflect some water into discharge opening 37, it will be appreciated that in the presence of a large volume of water inside of flywheel housing 18, some water will also be thrown in the direction of starter 35 and thus the starter is still subject to the above difficulties. Further, water may enter flywheel housing 18 through discharge opening 37 or may not be forced up conduit 39 with sufficient force to be completely discharged.

[0006] It would thus be desirable to provide an improved driving arrangement for a stern drive that will preclude the entry of water into the flywheel housing. It would be further desirable to provide a drive arrangement for a stern drive that provides a sealed flywheel housing relative to its surrounding environment to effectively insure against the entry of water into the flywheel housing.

BRIEF DESCRIPTION OF INVENTION

[0007] The present invention fulfills the foregoing needs by providing a stern drive propulsion system for a watercraft. The system comprises an internal combustion engine having a flywheel and a watertight housing sealingly enclosing the flywheel relative to the surrounding environment.

[0008] Therefore, in accordance with one aspect of the present invention, a sealed starter and flywheel arrangement for a marine propulsion system is provided. The arrangement includes a flywheel housing coupled to an engine block as well as a flywheel sealingly disposed within the housing. The arrangement further includes a starter supported by the flywheel housing and a starter seal sealing the starter to the flywheel housing.

[0009] In accordance with another aspect of the present invention, a stern drive propulsion.system includes a watertight enclosure having a flywheel disposed therein and a starter supported by the enclosure and coupled to the flywheel. The starter is supported by the enclosure and coupled to the flywheel such that the starter is positioned between an engine block and a rear transom of a marine watercraft. The system further includes a starter seal configured to seal corresponding interface surfaces of the starter and the enclosure.

[0010] According to yet another aspect of the present invention, a kit for a stern drive propulsion system including an internal combustion engine having a flywheel is provided. The kit includes a housing configured to provide a watertight enclosure for a flywheel as well as a starter connectable to the flywheel. The kit also includes a starter seal for sealing the starter to the housing.

[0011] In accordance with yet another aspect of the present invention, the stern drive propulsion system, includes means for sealingly attaching a flywheel housing to an engine block such that elements from an outside environment are resistant from entering the flywheel housing. Means for supporting the starter provided by the flywheel housing as well as means for sealingly coupling the starter to the flywheel housing such that the components within the starter are protected from exterior debris is also provided.

[0012] Various other features, objects and advantages of the present invention will be made apparent from the following detailed description and the drawings.

BRIEF DESCRIPTION OF DRAWINGS

[0013] The drawings illustrate one embodiment presently contemplated for carrying out the invention.

[0014] In the drawings:

[0015]FIG. 1 is a side elevational view of a prior art stern drive marine propulsion system mounted in a boat shown in partial cross-section.

[0016]FIG. 2 is a rear elevational view of the flywheel enclosure of the stern drive of FIG. 1.

[0017]FIG. 3 is a side view of a stern drive, in partial cross-section, incorporating the watertight flywheel housing in accordance with one aspect of the present invention.

[0018]FIG. 4 is a perspective view of the flywheel housing of FIG. 3 partially sectioned to view the flywheel.

[0019]FIG. 5 is a partial elevational view of a bottom section of the flywheel housing of FIG. 3.

DETAILED DESCRIPTION

[0020]FIG. 3 shows an exemplary marine propulsion system 100 having an internal combustion engine 102 located within a watercraft, such as a boat 103, having a transom 104 at a rearward end thereof. Standard engine mounts 106 attach engine 102 to boat 103. The engine 102 provides power to a drive shaft 108 that extends through the transom 104 of the boat. A gimbal housing 110 is mounted to transom 104. In one exemplary embodiment, gimbal housing 110 forms a part of the housing for a multiautomatic transmission 112 in a transmission housing 113. By incorporating a multitransmission with reverse gearing into the gimbal housing 110, the propulsion system is adapted to be used in place of a standard single speed inboard/outboard marine propulsion system. Two sets of planetary gears having a common ring gear may be used to provide a very compact two transmission with reverse gearing capability, thus permitting such a transmission to be packaged within the space provided by the gimbal housing of an inboard/outboard marine propulsion unit. It will be appreciated that for purposes of the present invention, the operation of the transmission need not be described in any greater detail.

[0021] As will be readily understood by those skilled in the art, the gimbal housing supports a gimbal unit 114, which includes a pivot housing 116 and a gimbal ring 118. Gimbal unit 114 is horizontally pivotable to provide steering to the boat in a desired direction of travel and is further vertically pivotable to provide, for example, a desired trim relative to the water plane over which the boat travels. Gimbal unit 114 accommodates a universal joint 119 therein comprising at one end thereof an input shaft, e.g., driveshaft 108, and having at an opposite end an output shaft 121 connectable to a propulsion unit 124, generally referred to in the art as vertical drive unit or outdrive, for allowing vertical and horizontal pivoting. Standard gears and driveshafts within outdrive 124 cooperate to transmit power from the output shaft 121 to a propeller shaft located in a lower gear case 123 appended at the lower end of drive unit 124 to drive propeller 125.

[0022] As shown in greater detail in FIG. 4, a flywheel housing 200 sealingly encloses flywheel 16 of the engine relative to the surrounding environment. Flywheel housing 200 supports a starter 202 coupled to flywheel 16. Flywheel housing 200 is interposed between engine block 102 and transmission housing 113. Flywheel housing 200 is a watertight housing and is free from any opening to the operating environment. It will be appreciated that this aspect of the invention prevents the entry of any water into the interior of the flywheel housing and thus avoids having to rely on any “water slinger” structure or water diverter such as that described with reference to FIG. 2.

[0023] An upper section of flywheel housing 200 supports starter 202. This arrangement avoids exposure of the interior of starter 202 to water that may leak into the bilge of the watercraft. To further ensure that the interior of the starter remains free from moisture, a starter seal 210 is provided to seal the corresponding interface surfaces of starter 202 and flywheel housing 200. Starter seal 210 may be a gasket or sealing ring. This arrangement prevents water entry through the interface and into the starter gear drive and starter engagement mechanism. It will be appreciated that the interior of the starter is thereby sealed relative to the surrounding environment.

[0024] Starter 202 has a proximate end 204 supported by the flywheel housing and a distal end 206 generally facing the transom of the boat. This arrangement adds to the ease of accessibility of the starter as opposed to the arrangement shown in FIG. 1. The prior art arrangement has the starter positioned axially inward relative to the transom of the boat. Removal of the starter shown in FIG. 1 may require time consuming and costly removal of the stringers of the boat to clear the engine block or disconnecting motor mounts and lifting the engine to clear the boat hull.

[0025] The present invention may require rotation reversal of a starter pin of a conventional starter that engages the ring gear of the flywheel to maintain the same flywheel rotational relationship relative to the engine crankcase in retrofit applications. As shown in FIG. 5, in one exemplary embodiment, a bottom plate 220 may be provided for sealingly closing a bottom section where the flywheel housing and the engine block interface with one another. If desired, a suitable seal ring 222 or gasket may be provided to enhance the, sealing capability of such plate.

[0026] The present invention has been described in terms of the preferred embodiment, and it is recognized that equivalents, alternatives, and modifications, aside from those expressly stated, are possible and within the scope of the appending claims. 

What is claimed is:
 1. A sealed starter and flywheel arrangement for a marine propulsion system, the arrangement comprising: a flywheel housing coupled to an engine block; a flywheel sealingly disposed within the housing; a starter supported by the flywheel housing; and a starter seal sealing the starter to the flywheel housing.
 2. The arrangement of claim 1 wherein the starter is coupled to the flywheel and the flywheel housing such that water is prevented from entering the starter.
 3. The arrangement of claim 1 wherein the starter seal includes at least one of an o-ring and a gasket.
 4. The arrangement of claim 1 wherein the starter has a proximate end supported by the flywheel housing and a distal end facing a transom of a watercraft.
 5. The arrangement of claim 4 wherein the flywheel housing is interposed between the engine block and a transmission housing.
 6. The arrangement of claim 5 wherein the flywheel housing further comprises a bottom plate sealingly closing a bottom section thereof and the engine block.
 7. The arrangement of claim 1 wherein the flywheel housing provides a watertight enclosure for the flywheel.
 8. A stern drive propulsion system comprising: a watertight enclosure having a flywheel disposed therein; a starter supported by the enclosure and coupled to the flywheel such that the starter is positioned between an engine block and a rear transom of a marine watercraft; and a starter seal configured to seal corresponding interface surfaces of the starter and the enclosure.
 9. The propulsion system of claim 8 wherein the watertight enclosure includes a flywheel housing and wherein an upper section of the flywheel housing supports the starter.
 10. The propulsion system of claim 8 wherein the watertight enclosure is interconnected between the engine block and a transmission housing.
 11. The propulsion system of claim 11 wherein the watertight enclosure further includes a bottom plate sealingly closing a bottom section thereof and the engine block.
 12. A kit for a stern drive propulsion system including an internal combustion engine having a flywheel, the kit comprising: a housing configured to provide a watertight enclosure for a flywheel; a starter connectable to the flywheel; and a starter seal for sealing the starter to the housing.
 13. The kit of claim 12 wherein the housing is configured to be interconnected between an engine block and a transmission housing.
 14. The kit of claim 12 wherein the starter seal includes at least one of a gasket and an o-ring.
 15. The kit of claim 12 wherein the starter is supportable in an upper section of the housing.
 16. The kit of claim 12 wherein the starter has a proximate end supported by the housing and a distal end facing a transom of a boat.
 17. The kit of claim 12 wherein the housing further comprises a bottom plate sealing a bottom interface of the housing and an engine block.
 18. A stern drive propulsion system comprising: means for sealingly attaching a flywheel housing to an engine block such that elements from an outside environment are resistant from entering the flywheel housing; means for supporting a starter provided by the flywheel housing; means for sealingly coupling a starter to the flywheel housing such that the components within the starter are protected from external debris. 